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Session 37: Triangles

Session Title

Triangle

Objective

By the end of the lesson, students will be able to:


  1.  Identify and name triangles based on sides and angles.
  2.  Understand that a triangle has 3 sides and 3 angles.
  3.  Discover and state that the sum of the interior angles of a triangle is 180°.
  4.  Collaborate in groups and reflect on their learning.

Concept

The world of triangles

Materials Required
  1. Pictures of triangle, square, rectangle, circle
  2. Instruments box
  3. Board & Chalk
  4. A4 sheet & Crayons 
  5. Work sheet

Methodology

Activity oriented

Session Duration

 90 Minutes

Introduction  Activity (15 minutes) 

Mandala Patterns 

  • Concepts: Circles, radial symmetry, angles, pattern repetition

How:

  • Students use compasses and protractors to make mandalas.
  • Emphasizes symmetry and repeated geometric patterns.
  • Can be colored for relaxing mindfulness activity too.

Example:(Draw the picture given below on a chart)

Main Activity (70 minutes)

What’s a Triangle?   Discussion (10 minutes)

Show pictures of different shapes (triangle, square, rectangle, circle).

Ask: Which one is a triangle? How do you know?

Students share prior knowledge.

Teacher highlights:

A triangle has 3 sides and 3 angles. It’s a closed shape.

Story Time :  (15 minutes )

In the Triangle Kingdom, every triangle has a secret code: its 3 angles must always work together to form a straight line (180°) to keep the kingdom safe!

Characters:-

  •  Prince Equi (Equilateral)
  •  Sir Righty (Right triangle)
  •  Lady Acuta (Acute triangle)
  •  General Obtusa (Obtuse triangle)

The sum of the interior angles of any triangle is always equal to 180 degrees.

In mathematical notation, for a triangle ABC with interior angles angle A, angle B, and angle C, the triangle sum theorem can be expressed as:

‹A + ‹ B + ‹C = 180⁰

Ask: Can you guess how their angles work together?  

Student Engagement:-    (10 minutes )

Ask students to act out triangle characters (e.g., stretch arms to represent different angles).

Key Concept : ( 10 minutes )

Definition of a triangle

  • A closed figure with 3 sides and 3 angles.

Types of triangles by sides

  • Equilateral (3 equal sides)
  • Isosceles (2 equal sides)
  • Scalene (no equal sides)

Types of triangles by angles

  • Acute triangle (all angles < 90°)
  • Right triangle (one angle = 90°)
  • Obtuse triangle (one angle > 90°)

Group Activity- Angle Detectives (20 minutes )

Make students into small groups(3 or 4)

  • Give each group a work sheet of  triangle with one missing angle.
  • Students solve for the missing angle by subtracting from 180°.

Review Questions(5 minutes)

  • What is a triangle?
  • How many angles does a triangle have?

Follow up Task (5 minutes)

  • Name a real-life object or structure that uses a triangle shape. Why is it used?

  • Draw a triangle where one angle is 90°. What type of triangle is it?

Expected Learning  Outcome:

Knowledge building-

  • This focuses on conceptual understanding and facts. You help students understand what a triangle is, its types, and properties.

Skill building-

  • Conceptual understanding

  • Problem solving

Resources

https://drive.google.com/file/d/1lkchm4tNLyq2JxJMW7rv2Si1XgdzZI7h/view?usp=drivesdk

 




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